/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package javax.servlet;

import java.util.EventListener;

/**
 * A ServletRequestAttributeListener can be implemented by the developer interested in being
 * notified of request attribute changes. Notifications will be generated while the request is
 * within the scope of the web application in which the listener is registered. A request is defined
 * as coming into scope when it is about to enter the first servlet or filter in each web
 * application, as going out of scope when it exits the last servlet or the first filter in the
 * chain.
 *
 * @since Servlet 2.4
 */
public interface ServletRequestAttributeListener extends EventListener {

    /**
     * Notification that a new attribute was added to the servlet request. Called after the attribute
     * is added.
     *
     * @param srae Information about the new request attribute
     */
    public void attributeAdded(ServletRequestAttributeEvent srae);

    /**
     * Notification that an existing attribute has been removed from the servlet request. Called after
     * the attribute is removed.
     *
     * @param srae Information about the removed request attribute
     */
    public void attributeRemoved(ServletRequestAttributeEvent srae);

    /**
     * Notification that an attribute was replaced on the servlet request. Called after the attribute
     * is replaced.
     *
     * @param srae Information about the replaced request attribute
     */
    public void attributeReplaced(ServletRequestAttributeEvent srae);
}

